http://www.pinnovators.com/catalog/product_info.php?products_id=54
I got one of these $120 with a $10 subwoofer cable kit from them and it works great on my Stern AC/DC Premium (SAM Machine).
I like it because it has volume control on the front of the coin door as well as a separate volume control for the headphones.
I can turn off all the sound from the machine and play with headphones only, which is a big plus at my house...